30 to 40% is fine. If it goes up to 50 for a day or so from raining, it's ok, nothing you can do about that. Make sure you're not misting in the tank a lot though as that can cause beardies to get an upper respiratory infection if the humidity is always higher.
So we have been told to spray our Bearded Dragon everyday because that is how they tend to get a lot of their water in nature. He really likes to lick the water off his head.
He did not take well to the change in living environments when we brought him home and did not self eat for several weeks. We had to force feed and did give him more frequent baths during that time. Still will not eat out of his enclosure but will eat when we place him in a separate smaller container.
We call Beardie a "he" but we don't really have confirmation at this point. He was 7 ¼ inches long when brought home. He was in a tank with quite a few dragons that they had gotten in that same week. We picked ours and they moved him to his own spot. We did not bring home right away because did not have setup complete and were traveling for a week. They said he was eating a ton when we picked I'm up. He is actually one of our kids' pets so we are glad that the eating is getting better cuz we can not hand feed forever
If he likes to lick the water off his head but is stressed when you move him or pick him up (my guy is the same way, he won't eat or drink out of his cage) you can spritz him (just on the head) in his tank then wipe out the extra water too.
a little bit of water sprayed in the tank isn't going to make a difference in humidity. if you have (good, digital) humidity guages, you can tell if it's causing any significant humidity spikes. and if your humidity is really low, say, below 20%, you might want to do extra baths or sprays to keep hydration up. but if you have a screen-top cage, water sprayed in there evaporates quickly and goes right up out of the cage. i've got gecko cages that i have to spray to get humidity up, and i have to cover most of the screen top or else the humidity drops right back down within an hour.
don't overspray, don't spray at night (when evaporation is slower and the moisture will linger longer) and you'll be ok. no need to spray daily but if he likes drinking droplets off his snout, that's fine. i use an eye-dropper to put it right on his snout, but that's more just to avoid wasting water.